Hey Claire, just tagging along too as I wrote a very similar post last week, DD is nearly 18m and still not regularly on one nap, mostly due to irratic nights, sometimes only 10.5 hours with NWs.
This week what has worked quite well for us is one 1 hour 45 min nap (if you can get one that long, I know it's hard and to be honest the only way I can get DD to take such a long nap is in her buggy!!) and an earlier than normal bedtime. Then if I don't get such a long nap I have been trying to get a later catnap. For instance yesterday she did:
A 7am
S 11.15am-12.30pm (earlier than normal nap but we were out in the car)
S 4-4.15pm
S 7.30pm
A "normal" day for the past week might be more like:
A 7am
S 12-1.45pm
S 7.30pm
Of course this doesn't always pan out exactly but like you I thought I should just finally bite the bullet and push for one nap, with the odd 2 nap day to balance things out if she was getting OT.
HTH you in some way and good luck with the rest of today. DD is at MIL's today where she never naps properly so my new "routine" will be out the window no doubt!
xxx
